I start the game fine, get through the menu fine, but when I choose "Act one" my SCREEN (Not just the game!) FLASHES FROM NORMAL TO BLACK several times about half a second apart.

Then, it stops. Then a message box appears.

Microsoft C++ Library or something like that is the title,

the message reads:"Runtime Error!

Program: (The directory for JoeDanger2.exe)

abnormal program termination"

It also happens in EVERY SINGLE RES. AND for every res IN WINDOWED OR FULLSCREEN.

AND it happens if I try to scroll my main menu to "Downloadable Tours" except without the flashing.

The window has "closed" but the music still plays for a few seconds after clicking ok or closing the message box, and "JoeDanger2.exe" is still an active process. Steam also thinks I am still playing it.

I've used about half my harddrive space so it can create a huge amount of save files.

I don't know how powerful my computer is but it can usually withstand a huge amount of lag that others usually get in games such as Minecraft with TnT, and my internet connection is 100MBpS. I have no idea what my problem is. I have all the most recent drivers.

Sounds like a problem with your MS VC Redistributable installation. Try uninstalling and reinstalling the game, if that doesn't fix it I would try fixing your VC redistributable installation by uninstalling and reinstalling the seperate packages manually, but that's a rather annoying and complicated process.